Party-girls turn single-mums

When former London society girl Birgit Cunningham lived in Los Angeles in the mid-1990s, she shared a house with two English girls desperate to break into Hollywood. One of them was Liz Hurley, then a struggling actress on the brink of fame.

It was a wild time in Birgit's life: she partied hard and, by her own admission, drank too much. As PA to a big studio exec, she hung out with some of the most famous movie stars in the world and even dated Kevin Costner. Coincidentally, Birgit also got to know the father of Hurley's child, Steve Bing.

"It's strange. I thought he was a really nice guy," she says now. "I was very happy to learn that the two of them started seeing each other later on." Of course, that particular relationship had a pretty nasty and very public ending, earning Steve Bing justifiable condemnation as a result. But Liz Hurley isn't the only party-girl-turned single mum, and Bing not the only wealthy absent parent.

Two weeks ago, 37-year-old Birgit also gave birth to a beautiful baby boy whose father, an English aristocrat named Harry Nuttall, hasn't seen him once. Lacking a father's input, she's decided to call her son Jack. The result of her two-year relationship with Nuttall, Jack now lives with Birgit in a tiny, one-room rented bedsit with no prospect of meeting his rich paternal grandfather, Sir Nicholas Nuttall, a baronet, and not a card, bouquet or even a phone call from 39-year-old Harry.

So thoroughly has Nuttall disappeared from Birgit and Jack's life that it was only by accident, says Birgit, that she learned of his marriage this very weekend to the beautiful Swedish bond trader, Dalit Cohen. It is not known whether the bride, or the wedding guests, are aware that Nuttall is a new father.

Birgit's colourful past isn't only the stuff of gossip columns and Hello! magazine chatter. It also exposes the superficiality and immaturity of a particular London set, the Chelsea boys and girls, whose rich, often aristocratic, parents fund a life of partying and playing, and apparently foster little sense of responsibility.

"You wouldn't believe how many of my girlfriends have ended up in this position," says Birgit, as Jack lies on the sofa-bed, gurgling happily. "A lot of those men are what we call 'modelisers'. Often they can't really talk to a woman if she's older than 18. I've dated lots of guys who've dated models, and they're very immature and commitment-phobic. Well, Harry reigned supreme for immaturity." Up to the moment she became pregnant, Cunningham's life resembled nothing so much as a fast-paced chick-lit novel. Her cutglass accent belies her American roots: she was born in San Francisco, her father a successful, high-profile banker, then moved to England where she was educated at Roedean.

As a wildish twentysomething in London, she began a career as a yacht broker in the City, and as a serial dater of trust-funded, Chelsea-based bachelors. She went out with tycoon Robert Hanson and others of his well-heeled ilk; she turned up at every party and every rich kids' nightclub.

"I think I could easily have been defined as a gold-digger back in the Eighties," she says sheepishly. "It was an indulgent scene and I was just blasè about it. I was pretty spoilt, to be honest, and thought quite a lot of myself in those days."

Harry Nuttall, she says, "was just about the poorest man I ever dated. He didn't really register on my Richter scale". Nevertheless, his green eyes and blond hair, his Old Etonian manners and better than average skill on the dancefloor, attracted her attention. They first started dating 10 years ago, when Harry, whose wealth is not to be sniffed at, was racing Formula 3 cars for a living. In a panic of uncertainty about the direction her life was taking, however, Birgit eventually called it off and moved to LA, to see how far she could get in Hollywood.

The answer was really quite far, but at a price. Birgit got a good job at Universal Pictures and earned the envy of countless women by going out with Costner - but also acquired a drink problem and, very briefly, a German husband whom she married in Las Vegas on a whim. "I took it to the limit. They do everything to the extreme in LA. Either you're wild or you're a health nut. And if you change from one to the other, you wave all your friends goodbye and have to start again."

When she came back to London in 1997, she stopped binge drinking and turned herself into a web designer at the very height of the internet boom.

At the same time, with an enviable facility for spotting trends and turning them to her advantage, Birgit became an environmentalist, working briefly for Zac Goldsmith's magazine, The Ecologist, and, later, becoming PR to the Green Party at the Greater London Assembly.

Remember the young, glamorous blonde who threw a chocolate èclair at Nick Brown, then agriculture minister, at the fusty National Farmers' Union conference in 2000? That was Birgit, in a fury at Labour's apparent dismissal of the crisis in farming. "It was going to be a millefeuille," she says, laughing, "but I couldn't fit it into my handbag."

Harry Nuttall, meanwhile, was dating models. Indeed, he married one of them, American beauty Kelly Allen. The marriage didn't last, however, and Harry's list of conquests grew ever longer. He went out with German model Karen Mulder, and even turned muse to Candace Bushnell, the creator of Sex and the City, who based one of the stories in the book Four Blondes on their relationship.

When Birgit and Harry hooked up once more in London, 10 years after their very first date, they had both grown older and a little wiser. Their friendship renewed, and for two years they had a relationship of sorts.

"We started sleeping together because we were really good friends, and I was certainly led to believe that he wasn't sleeping with anyone else. But I didn't see him very often, and so although that was the understanding, I kept it really open with him. When I was dating Kevin Costner, it was the same scenario, so I'm used to that kind of thing."

She pauses for a moment. "I don't know why I do that to myself. I suppose I'm so used to giving men space. When you've dated some of the men I've dated, you're used to keeping your mouth shut and that's probably ruined me.

"Harry took me to one or two restaurants, but usually he'd call me on a Sunday or a Monday. I was his Sunday night girl. I'd go round to his place and we'd order sushi and watch a video. Then he'd call me up and say, I'm off to St-Tropez, or I'm off to a wedding in Venice, and I'd pause, waiting for an invitation - but it never came.

I have a few girlfriends who say their boyfriends do the same thing: it's the strangest Chelsea habit.

"I wasn't going to say that I loved him, but I did. All the same, I didn't tell many friends about the relationship because he definitely wasn't introducing me to people he knew."

I ask her whether it ever occurred to her to question his behaviour. "I was always slightly aware of the fact that I wasn't a model," she says. "He kept talking about the famous people he'd met, and all the models. I was starting to feel a bit insecure about not being one."

The pregnancy was an enormous shock. Birgit had been on the pill for three months, only missing taking it when she was suffering from flu. She then found herself locked out of the jobs market because of the baby. She told Harry about the pregnancy over the phone and at first, she says, he seemed delighted. They went out to dinner and talked it over: "He asked me whether I was sure about it, but he didn't ever tell me not to have it.

"We discussed schooling, that kind of thing. He said: 'If it's a boy, we'll send him to Eton, and if it's a girl, it doesn't really matter.' It was certainly a much bigger deal for him to have a boy."

After that, while Birgit felt relatively at ease with the situation and perhaps naively trusted Harry's Old Etonian sense of decency, she waited for him to call again. But he didn't, she claims, not once. Their relationship, always conducted primarily by phone and initiated by his calls, crumbled. So she phoned him on odd occasions to tell him that, yes, she was being sick every day and, yes, she was getting fatter.

But he'd always find an excuse to hang up, she says, and then simply fail to call back. Birgit spent Christmas in Bosnia where her father was working, while Harry went to South Africa. Later, she sent him a copy of her 20-week scan, a remarkably clear photo of Jack's little face - gift-wrapped in an Asprey and Garrard box, but once again received no reply.

"I was starting to get very weepy," she says. "I couldn't believe he wasn't going to call me, that he didn't want anything to do with me. Not once did he ask how I was, or how the baby was." In February, she flew back to LA to see her old friend Kevin Costner, who gave her advice and let her cry on his shoulder.

A little later into the pregnancy still, Birgit discovered that Harry had met Dalit Cohen, an ex-girlfriend of Robert Maxwell's son, Ian, on holiday at Christmas and had promptly become engaged - a stunning piece of news that caused what she thinks was a panic attack. She went into hospital for a day with breathing problems.

When the baby was born, Birgit rang Harry from her hospital bed and left a message telling him that he had a beautiful baby son. Earlier this week, with Jack in her arms, Birgit rang Harry again to ask him whether he'd like to see his newborn son. "He said no. In fact, he said: 'Don't you think you're being insensitive? I'm getting married this weekend.'"

Marriage was never an issue for Birgit herself. She was well aware that Harry Nuttall, who refused to speak to the Evening Standard, wouldn't marry her, and she wasn't much bothered by it. But she had expected some moral support from him. Even now, on her own in her bedsit, travelling by bus and using the local laundrette, like thousands of single mums all over the country, she wants him to have a relationship with Jack.

"I know I'm better off without Harry, and I wish all the luck in the world to his new wife, because she's going to need it," she says. "I think it's imperative that she knows how Harry has behaved towards me. But I'd still forgive him everything for Jack's sake.

"He always paraded himself as a gentleman," she adds, "but I've discovered that nobility is in what you do rather than whose furniture you've inherited." A sentiment with which Birgit's former housemate Liz Hurley might well agree.